Based on data published by Ministry of Health on major causes for death among Chinese urban and rural residents during 2007-2012, the top three causes for death among urban residents are malignant cancer, cerebrovascular disease and heart disease, while the top three causes for death among rural residents are malignant tumors, cerebrovascular disease and respiratory diseases, wherein mortality due to malignant cancer is steadily rising. Accordingly, malignant cancer has become the leading cause for death of Chinese residents, and its development is accelerating.
In recent years, along with deepening life science research and the rapid progress, receptor tyrosine kinases, which exhibit aberrant activation in cancer, has become an important target in the anticancer drug research and development because of the critical roles they play in tumorigenesis, invasion and metastasis, drug resistance, etc.
Protein tyrosine kinases (PTKs) are closely related to tumor development and progression. Protein tyrosine kinase hyperactivity may cause activation of downstream signaling pathways, in turn, lead to cell differentiation, proliferation, migration, and inhibition of apoptosis, and eventually, result in tumor formation and metastasis [Top Med Chem, 2007 (1): 83-132]. Accordingly, protein tyrosine kinase inhibitor has become one of the fastest growing class of anticancer drugs, having a number of small molecule protein tyrosine kinase inhibitors including lapatinib, sunitinib, crizotinib and the like marketed by the end of 2012. Compared with conventional cytotoxic anticancer drugs, these drugs exhibit improved selectivity, higher efficacy, less side effects, and have become the hotspot in anticancer drug research.
Hepatocyte Growth Factor (HGF) receptor c-Met is an important member of the receptor tyrosine kinase family. HGF is overexpressed and abnormally activated in most cancers and some sarcomas, closely associated with poor prognosis in patients having cancer, such as lung cancer, stomach cancer, liver cancer, breast cancer, colon cancer, prostate cancer, pancreatic cancer, esophageal cancer, ovarian cancer, kidney cancer, glioma, thyroid cancer, melanoma, etc. Upon activation through interaction with HGF or otherwise, c-Met induces tumor cell proliferation and resistance to apoptosis, promote tumor cell migration, invasion, and angiogenesis (Nature Reviews Drug Discovery 2008, 7, 504-516; Nat Rev Cancer. 2012; 12 (2): 89-103). Unlike other kinases, c-Met, a critical node in tumor signaling pathways, may interact with other tumor-associated molecules on cell surface to activate and magnify tumor-related effects through crosslinking, and promote tumor development and metastasis (Nature Reviews Drug Discovery 2008, 7, 504-516.). In addition, abnormal activation of HGF/c-Met is closely associated with resistance to inhibitors against EGFR, HER2, and B-Raf as well as some chemotherapeutic drugs (Science 2007, 316, 1039-1043; Clinical Cancer Research 2011, 17, 2260-2269; Nature 2012 Jul. 26; 487(7408): 500-4; British Journal of Cancer 2012, 107, 793-799). Accordingly, investigation targeting c-Met inhibitors has become one hot frontier in anticancer drug researches.
Therefore, there is an pressing need for development of novel protein tyrosine kinase inhibitor having new structure, high activity, and low toxic side effects. As a receptor-type protein tyrosine kinase, c-Met is expressed in both normal cells and tumor cells. Normal HGF/c-Met signal transduction plays an important role in embryonic development, tissue repair, whereas abnormal HGF/c-Met signal transduction is closely associated with tumorigenesis, especially, with invasion and metastasis (Gao G F, Vande Woude G F. HGF/SR-Met signaling in tumor progression, Cell Res, 2005, 15(1): 49-51). Overexpression of c-Met is found in human hepatocellular carcinoma, cholangiocarcinoma, pancreatic cancer, lung cancer, thyroid cancer, pleural mesothelioma, etc., especially in metastatic tumors. Its role may include impacting adhesion of tumor cells, promoting degradation of extracellular matrix, inducing angiogenesis and promoting cell proliferation. All these indicate that c-Met is an important target for cancer therapeutics. Currently, blocking HGF/c-Met signal transduction is an important strategy for antitumor therapy. Since c-Met inhibitors, especially small molecule inhibitors as anticancer drugs are mostly in clinical studies and yet to be marketed, and antibody drugs are often more expensive, a broad space is available for development of these inhibitors. Accordingly, c-Met kinase is a promising target for anticancer drug researches. Although many inhibitors are developed against this signaling pathway, their structures are rather confined. This application designs a new class of 5-member-heterocycle fused pyridine compounds and discover that they possess desirable c-Met inhibitory activity.